How come there are no blue or green mammals?

Have you ever thought about this? Think about it for a minute. If you were to list 10 mammals off the top of your head – perhaps animals like your dog, cat, an elephant, rat, zebra, skunk, raccoon, opossum, bobcat, or even a coyote – you would quickly realize that the colors of these mammals lack blue and green hues. There are a couple of reasons as to why this is, and why other animals like insects, birds, amphibians, and reptiles exhibit these colors quite often.

The reason has to do with chemistry primarily. First off, let’s talk about what produces colors in living things. Pigments are chemical compounds that are responsible for producing color in the biological world. When pigments absorb light, they reflect back certain wavelengths, producing colors our eyes can perceive. Plants, for example, have many different kinds of pigments with all kinds of peculiar names, such as carotenoids, flavonoids, and anthocyanins. Thousands of these chemicals have been identified by scientists and this is the reason why plants can produce a vast array of colors – from the dominant green leaves, to different shades of bark on trees, to the orange color of a carrot, the colorful fruits and flowers there are and the beautiful foliage colors we see during autumn in temperate latitudes.

When it comes to animals however, things are a bit different. The vast majority of animals simply do not have the variety of pigments that plants do. Specifically, they are not able to genetically produce blue and green pigments. Then how come we still see animals that are those colors? There’s blue butterflies, green frogs, and peacocks are well-known for their blue feathers! Most of these animals produce this color through a phenomenon known as structural coloration, which is the optical illusion of a color, essentially. Small structures of the skin scatter and reflect back light in a way so that only the blue wavelengths reach our eyes. But, in reality, there is no blue pigment doing that. When it comes to green, usually there is a yellow pigment involved with a structural blue coloration.

For instance, when a rough green snake (Opheodrys aestivus), a common River Legacy snake, dies, it turns blue because the yellow pigment is no longer being produced but the structural color is still there. Another way animals are able to produce vibrant colors is by obtaining pigments from their environment, typically their diet. This is how flamingos develop their typical pink to red hue, by eating foods like algae, shrimp, and crabs that have these pigments in them. A similar phenomenon occurs with the northern cardinal (Cardinalis cardinalis), another River Legacy common sight.

Now, let’s go back to mammals. Mammals have not been able to evolve or have lost the ability to implement pigments obtained through their diet to the same extent as other animals have. It happens but not to the same degree. This is why eating something like beets can turn the toilet a certain color when we go to the bathroom but it does not turn our skin purple. When it comes to naturally-produced pigments, mammals really only produce one kind – melanin. Melanin is an important pigment that provides protection against the sun’s damaging UV rays but it also is responsible for the majority of colors in mammalian skin. It comes in two kinds – eumelanin (responsible for black and brown colors) and pheomelanin (responsible for yellow or reddish to brown colors). Very few mammals, like mandrills (a type of African monkey), are able to produce small amounts of blue color through structural coloration.

But, how come no other mammals can? Scientists are not really sure but it may have had to do with the evolutionary history of mammals. Early mammals survived during the Mesozoic era, the golden age of the dinosaurs, by basically not being around them too much in order to avoid becoming food or by not trying to compete with them for the same resources. It is believed that most dinosaurs were active during the day so it is most likely that mammals had to turn to a largely nocturnal lifestyle. This meant that mammals did not have the need to develop adaptations that were not necessary in the night, such as the ability to see a wide range of vibrant colors. If there was no selective pressure (i.e. need) for either evolving structural coloration, pigment formation, or the ability to obtain pigments through diet, then the genes that allowed for those traits disappeared from the mammalian gene pool. The majority of animals today, with the exception of most mammals, have stellar color vision. On the other hand, as a result of their evolutionary history, mammals tend to be color-blind when it comes to blue and green colors. The big exception to this are primates – the group to which humans and mandrills belong. Therefore, it is hypothesized that as a result of all of this, the vast majority of mammals lack green or blue colors on their skin or fur.

What an incredible and fascinating subject to be sure. Next time you take a hike in the River Legacy trails and you come across a mammal – whether it be a squirrel, bobcat, or rabbit – you will know why those creatures are not flashing blue and green at you!

Hibernation or brumation?

How do animals survive the winter? Winters at River Legacy tend to be milder than in most places around the country because of our location. Still, there are periods when the temperature drops to well below freezing and, sometimes, lingers there for days. Snow and ice events are also expected at least a couple of times during the winter.

Birds have adaptations for surviving the winter that are unique to them. We will talk about them in an upcoming post! For now, we are going to be focused on mammals, reptiles, and amphibians. All of these groups go into a state of dormancy during which they stop growing, grind their physical activities to a halt, and their metabolism significantly slows down. But there are differences in how each group does it.

Hibernation refers to the process mammals go through whereas brumation applies to

Reptiles, such as this red-eared slider (Trachemys scripta elegans), brumate during the winter

reptiles and amphibians. During hibernation, mammals go into a full state of sleep. They slow their breathing and heart rate down to almost full stop and rely on fatty deposit for their energy during this time. They do not wake up from hibernation at all until spring arrives. How do they get their fatty deposits? By eating more and more in the fall. Bats are really the only group that lives at River Legacy that truly hibernate. Other River Legacy mammals such as bobcats, skunks, fox squirrels, coyotes, raccoons, and opossums do not hibernate and instead just seek shelter in someplace warm and do not come out very much OR are able to be fairly active while winter lasts.

Bats, such as this Eastern red bat (Lasiurus borealis), are the only River Legacy group of mammals that truly hibernate.

Brumation, on the other hand, is the process by which reptiles and amphibians survive the winter. During brumation, these animals slow down as well but not to the point of almost stopping heart rate and breathing altogether. One key difference between brumation and hibernation is the fact that brumating animals are able to wake up from time to time in the middle of the winter. This is known as punctuated activity. Why do they need to wake up from time to time? Unlike mammals, which can survive the winter without water, reptiles and amphibians need it periodically. Another key difference is found in the method by which the animals obtain their energy. Mammals, as mentioned, rely on fatty deposits. Reptiles and amphibians instead use glycogen for their energy needs. Reptiles also can survive with very little oxygen during brumation because of this glycogen storage. Examples of River Legacy reptiles and amphibians that brumate include frogs, toads, snakes, and turtles.

If you would like to learn more about the winter adaptations of mammals and reptiles, we invite you to join our Winter Break Activities that are going to take place from December 26th through the 28th. For more information, please visit www.riverlegacy.org/calendar. We hope to see you there!

 

Recent Bobcat Sightings

Bobcats (Lynx rufus) are well-known inhabitants of our woods! These cats are usually very secretive but, every once in a while, they are spotted walking openly on our paved trails where people can see them. Unlike most mammals, bobcats are still active despite the increasingly colder days. During fall and winter, they become more diurnal as their prey (rabbits and rodents, mainly) is more active at daylight during those seasons. So, it is possible that more bobcats are going to be seen in the next coming weeks and months. Bobcats, in general, are not aggressive species. It is incredibly rare for bobcats to present danger to people. Nevertheless, here are some things you should know if you happen to encounter a bobcat:

  • Stay within a reasonable distance of the bobcat. If you start getting too close to it, it might think you present a threat. Naturally, it would want to defend itself.
  • If the bobcat starts to walk toward you, which is incredibly rare, slowly start backing away. It is important that you do not run as this might scare the bobcat.
  • Do not touch or attempt to feed the bobcat. Bobcats are wild animals and you always want to minimize opportunities for them to bite. As it is the case with most wild mammals, wild bobcats may be rabid at times. Feeding any wild animal can cause harm to the animal, and there are plenty of food resources in River Legacy Park.
  • If a bobcat decides to walk by you, as long as you do not try to kick it or make sudden movements, the bobcat will just continue on its way.
  • Always have your pets on a controlled leash. The last thing you want is any altercation between a wild bobcat and your dog.
  • Be sure to take a picture and/or video of your bobcat encounter from a safe distance!

Seeing bobcats is a neat experience and if you find yourself in that situation and, as long as you follow these precautions, you will be able to enjoy being in the presence of these wonderful cats!

 

Bobcat (Lynx rufus) seen near the entrance of River Legacy Living Science Center last Saturday, November 10th, 2018!

The Armadillo and the Bobcat

 

 

 

 

 

 

 

Exiting the back doors of the Science Center, I headed out for a walk. To my right was a Texas persimmon, bordered by layers of the scarlet turk’s cap, a beautiful plant with flowers deeply red. The large stone steps escorted me down to the level of the trails.

Overhead hung vines, whose mustang grapes quietly tumble to the ground and are squished by herds of wandering feet. I walked further, passing the American pokeweed, a plant which hides its toxicity behind its blueberry-like appearance. To my left, a forking trail leads to an alleyway of poison ivy, appropriately labeled so that onlookers can observe without risk.

Finally, I reached my destination – the pedestrian bridge, whose sturdy wooden panels are upheld by the strength of red metal framing. Beneath this bridge flows Snider Creek, which on this day was dry from weeks of Texas heat and drought. I leaned over the edge to look.

Along the dry creek bed I saw movement. What was this bizarre creature? A medium-sized body, slender, coated in a thin layer of light brown fur. I struggled to identify it. But as it turned its head upward, facing me, the uniqueness of its facial structure with its tufted ears, disclosed its identity. I was looking at a bobcat, my first time seeing one in the park.

I was mesmerized by this sighting; I’d wanted to see a bobcat for quite some time. But as the cat ran away, and I began to excitedly return to the building, I heard another noise, this time along the bank that lines the creek. I looked to my left to see an armadillo just beside the bridge digging in the dirt, slowly heading in the same direction as the bobcat.

What an incredible walk this had been. To see a bobcat in the park is a rare privilege, but to see one within 50 feet of an armadillo is remarkable. These creatures are vastly different. Both are mammals, but that concludes their overlap. One is lengthy and thin, walking with the elegance of the feline family. The other is spherical and armored, trudging along. How strange, then, to see these incredibly different animals in such close proximity.

But this is what one encounters along the River Legacy trails. Each walk is different. Some are calm and quite; others are filled with the humming of cicadas and the chirping of birds. During some, one sees young turtles, ribbon snakes, or eastern cottontail rabbits. On a rare occasion one might spot a beaver wading in the pond, its uppermost layer of fur made dark by the water. And on some lucky days, as I was fortunate enough to experience, you may see the astounding variation of the natural world displayed in front of you, as bobcats and armadillos wander along the same creek.

Come visit our trails and let us know what you find.

Written by Josh Ripple, a Summer Intern at River Legacy Living Science Center and student at Stanford University.

Meet a Few of Our Wildlife Ambassadors!

Smokey the Western Rat Snake

Hi guys!! I am Smokey, a Western Rat Snake. I am the newest Animal Ambassador to River Legacy Living Science Center and the latest resident to our public exhibits. I was brought from the Fort Worth Nature Center because I needed a larger home.

I am 6 years old with a beautiful yellowish, tan color and irregular blotching from head to tail. I am active during the day, especially when I’m hungry! Hey, you can come see me eat every Friday at 4:30! Sometimes when I get disturbed I let out a hiss, but not to worry, I‘m not venomous, merely voicing my opinion.

Actually, my relatives and I get confused with rattlesnakes because we look alike and we both shake our tails, but Western Rat Snakes do not actually have a rattle. Generally, though, I am a nice girl so come on over and see me! I am so excited that I just got a larger home with lots of room to climb! I might be hiding up high, so look closely.

 

 

 

Poppy the Virginia Opossum

Poppy the Virginia Opossum found her way to River Legacy Living Science Center after she was rescued and rehabilitated from being hit by a car. Due to the injuries sustained, she was not able to be released back into the wild. This is unfortunate due to the many positive benefits opossums provide to an ecosystem.  She is very sweet and curious about her new home. She loves eating hard-boiled eggs, crickets and strawberries.

When people encounter this ambassador in the wild, the feelings are a mixed bag. Some think this nocturnal creature is either cute or ugly; others think it looks like a giant rat. The Virginia Opossum (Didelphis virginiana) is a very unique creature. It is North America’s only marsupial, which means it has a pouch. Average life span of a wild opossum is 1 to 3 years; life span of a captive opossum is 2 to 5 years.

Opossums have a remarkably robust immune system and show partial or total immunity to the venom of rattlesnakes, copperheads, and other pit vipers. (Remember, North Texas only has two venomous snakes, the rattlesnake and copperhead.)  Opossums are about eight times less likely to carry rabies than wild dogs. This is due to the fact that their core body temperature is lower than most mammals and the virus cannot live in this cooler environment.

Another benefit from having opossums in your neighborhood is that they will eat and therefore kill ticks that are in their fur.  Opossums are fastidious groomers.  A study by the Cary Institute for Ecosystem shows that an opossum may eat up to 5,000 ticks in a season. Ticks can cause a variety of issues for humans, including Lyme Disease.  Now, the opossum is not single-handedly stopping Lyme Disease, but if the opossum takes care of ticks in its own body, then those are less ticks in our yards and natural areas.

Beavers at River Legacy!

River Legacy is home to lots of very well-known mammal species such as bobcat, raccoon, squirrel, and armadillo. But, did you know that the North American beaver (Castor canadensis) also lives here? Here are some cool facts about one of River Legacy’s most secretive mammals.

  • Beavers are the second largest members of the rodents, after the South American capybara. They can weigh up to 71 pounds!
  • Beavers have an extra thick layer of fat under their skin. This helps with insulation from very cold water.
  • Beavers are incredible architects! They are able to construct their homes in rivers, streams, and/or lakes using twigs, mud, sticks, chewed-on trees, and other similar materials.
  • Beavers can remain underwater for up to 15 minutes!
  • Beavers can use their tail to slap it on the water to warn other beavers nearby of potential danger, such as predators.

Beavers are largely nocturnal. The best way to find them during the day is during the dawn hours. Walking the trails close to the Trinity River or Snyder Creek during this time could provide you with the wonderful experience of seeing a beaver! We’ve even spotted one in our pond recently at River Legacy Living Science Center!

Learn more about the beaver and other animal architects during our NEW Animal Architects Summer Class in July. Spaces are still available for the class which meets July 9-13 and July 16-20. Sign up online at www.riverlegacy.org or call 817.860.6752, ext. 102 to enroll today!

Bird winter migration is here!

Late fall and winter are perfect opportunities to go birding and see species not seen typically at other times during the year. Several species of birds are now migrating south to spend winter in warmer places. River Legacy sits right in the heart of the Central Flyway, which is one of the main bird migratory routes in North America.

Some of the birds that can be seen this time of year include the cedar waxwing (Bombycilla cedrorum), white-throated sparrow (Zonotrichia albicollis), ruby-crowned kinglet (Regulus calendula), yellow-rumped warbler (Setophaga coronata), lesser scaup (Aythya affinis), northern shoveler (Anas clypeata), and hermit thrush (Catharus guttatus), among others.

In addition to these birds, other common species such as the downy woodpecker (Picoides pubescens), northern cardinal (Cardinalis cardinalis), Carolina chickadee (Poecile carolinensis), and  great blue heron (Ardea herodias) can be seen this time of year as well.

River Legacy is the perfect place to check some winter species off your list.  In fact, from December 14th to January 5th, thousands of people around the nation are engaging in bird counts for the annual Christmas Bird Count. In addition, we encourage you to visit us February 17th for our Great Backyard Bird Count Festival. River Legacy is proud to participate in this global count, hosted by the Cornell Lab of Ornithology and the National Audubon Society. There will be bird counts, games, crafts, and activities celebrating the avian world.

Lastly, make sure to keep up with the latest bird sightings at River Legacy by following our Birding Blog, which can be accessed through the link to the left of Nature Notes Blog on our website. Happy winter birding!

Downy Woodpecker

Female Lesser Scaup

What is basking?

Whenever you take a walk through the woods, you might see lots of reptiles and amphibians enjoying a sunbath. Turtles usually gather on top of a log, all lined up neatly one behind the other. Sometimes, they decide to take in the sun just off the side of a creek or river. Snakes and lizards usually like to receive the sun’s heat just off the side of a trail or on top of a log or surface. Amphibians, likewise, exhibit similar behavior.

But, have you ever wondered why these particular animals do this? What reptiles and amphibians are doing is called basking. Basking is the action of receiving warmth directly from a heat source, such as the sun or a heat lamp, by simply standing or sitting under it. Both reptiles and amphibians are ectotherms, which means that they are not able to regulate their own body temperature in the same way that other vertebrates, such as mammals or birds, can. Sometimes, this is also referred to as being “cold-blooded.” Their body temperature basically depends on their environment. Basking allows these animals to be able to obtain the energy that they need in order to move about, find food, mate, and all the other things that they need to do. This is the reason why, if a reptile or amphibian gets cold, it starts acting in a very sluggish manner.

Next time you visit River Legacy Living Science Center, take a close look at our pond. In it, you will find a small island in the middle that is a very popular spot for basking turtles. You can also search for basking lizards on any surface where the sun is hitting.

Amphibians of River Legacy

River Legacy is home to a wide variety of animals. Though big mammals and such as armadillos, bobcats, raccoons and others are among the most iconic inhabitants of River Legacy, several equally-awesome amphibian species make this park their home.

But, first, what are amphibians? Amphibians are a class of vertebrates (animals with a backbone) that are cold-blooded, live semi-aquatic lifestyles, and have a moist and scale-less skin. There are three kinds of amphibians in the world: frogs and toads; salamanders; and caecilians.

Gulf Coast Toad

Here,  only two of those kinds can be found – frogs and toads and salamanders.

Frogs and Toads

Several frog species can be found in our forest. Frogs and toads will usually be found near or in a body of water or a moist area. Some can be seen hopping by the trails or in our pond. Here are some of the most common species: Gulf coast toads (Incilius valliceps) are native to Central America but they have become established in North-Central Texas, including River Legacy. Other common species include the southern leopard frog (Lithobates sphenocephalus) and the American bullfrog (Lithobates catesbeianus). Additional species include the Texas toad (Anaxyrus specious), green tree frog (Hyla cinerea), gray tree frog

Blanchard’s Cricket Frog

(Hyla versicolor), and the Blanchard’s cricket frog (Acris crepitant blanchardi).

Salamanders

Salamanders look like lizards but they are not covered in scales. They are less diverse and common than frogs and toads. One of the common species found in River Legacy is the barred tiger salamander (Ambystoma mavortium).  River Legacy is part of the range of other species, but no records have been reported.

Visit River Legacy Living Science Center to see the amphibians in our animal exhibits!

Why Do Nocturnal Animals Come Out at Night?

As with most animal behavior, it comes down to survival. Whether it’s avoiding being eaten by another animal or being able to find food, nocturnal animals have plenty of good reasons to sleep during the day and hunt at night.

Temperature

Many reptiles sleep during the day to avoid the hot afternoon temperatures. For example, Copperhead snakes spend much of the daytime sleeping under logs and leaf litter. Then they forage for cicadas and small rodents at night.

Predators

Animals such as mice are nocturnal because many of their predators are out during the day. While there are also predators at night, these small animals have a better chance of going unnoticed as they forage for food and water. During the day they can rest safe and sound within their burrows and at night they can search for food.

Prey

Some animals also come out at night because their prey comes out at night. For example, owls hunt for mice at night, which also happen to be nocturnal. Catching prey at night can be more difficult, but nocturnal predators are equipped with adaptations like great hearing and eyesight.

Competition

Animals are nocturnal because there is too much competition during the day. For example, bobcats might hunt during the daylight so coyotes hunt at night. This allows each species the chance to hunt for food without constantly fighting each other.

The coyote picture shown above is from one of our night trail cameras at the Science Center which captures still photographs. Trail cameras are predominately used to watch and track wildlife. They are perfect to place in a remote location and see what wildlife is in the area. It is surprising what you will see and how much wildlife is around us at night.